The present invention relates generally to semiconductor fabrication and, more particularly, to a chemical mechanical (CMP) system and method for preparing a wafer in a cleaning module.
In the fabrication of semiconductor devices, there is a need to perform chemical mechanical polishing (CMP) operations and wafer cleaning. As is known to those skilled in the art, CMP is used to planarize globally the surface of an entire semiconductor wafer. After a CMP operation, residual particles or films are left on the surface of the wafer. These residual particles or films may cause defects such as scratches on the wafer surface which may cause devices on the wafer to become inoperable. To avoid damaging the devices, the wafer needs to be cleaned after the CMP operation.
FIG. 1 is a simplified schematic diagram of a conventional CMP system 10 and cleaning station 18. During the fabrication of semiconductor devices, a number of CMP operations are typically carried out (e.g., bulk copper removal, end-point detection (EPD) and over polish, barrier removal, buffing, etc.), and each CMP operation has a unique process requirement. To maximize CMP system performance, CMP system 10 typically includes several CMP modules with each module uniquely optimized to meet the requirements for each CMP operation (e.g., customized process conditions and consumables).
As shown in FIG. 1, CMP system 10 includes a first linear CMP module (LPM1) 12, a second linear CMP module (LPM2) 14, and a third linear CMP module (LPM3) 16. In a typical configuration, LPM1 12 is configured for bulk copper removal, LPM2 14 is configured for EPD and over polish, and LPM3 16 is configured for barrier removal and buffing. After the CMP operations, CMP system 10 feeds the wafer to cleaning station 18 for cleaning. As is known to those skilled in the art, cleaning station 18 cleans the wafer by scrubbing with selected chemicals and water (e.g., de-ionized (DI) water).
One problem with the conventional setup of having separate systems specialized for CMP operations only or cleaning operations only is that the setup requires numerous, specialized modules within the CMP system or multiple functions to be performed within each module. Each additional CMP module or modules with multiple functions add to the size and complexity of the CMP system. Furthermore, transferring the wafer from one module to another module decreases throughput.
In view of the foregoing, there is a need to simplify the design and process of CMP systems and to increase throughput.